1. Field of the Invention
The present invention relates to a photosensitive member for electrophotography.
2. Description of the Related Art
In general, a photosensitive member for electrophotography comprises an electroconductive support on which a photosensitive layer and a surface protection layer, if desired, are formed. Because external mechanical force is applied to the surface of the photosensitive member when a toner image formed thereon is transferred to a transfer medium such as paper, or when the residual toner is cleaned off of the photosensitive member, photosensitive members are required to have surface durability against wear and impact (wear-resistance). Accordingly, a technology is known in which, in order to improve the wear-resistance of the conventional photosensitive member, the outermost surface layer of the photosensitive member is embedded with small particles of a fluorine-containing resin (hereinafter, referred to as “fluororesin”) such as polytetrafluoroethlyene (PTFE) resin.
In particular, a technology has been reported (see, for example, Japanese Patent Application Laid-Open No. 8-328287) in which fluororesin particles having a low degree of crystallinity (i.e., an X-ray diffraction pattern peak half-value width of 0.28 or higher) are used as means to effectively reduce the friction coefficient of the surface of the photosensitive member and improve wear-resistance. However, this technology entails the problem that it is difficult to disperse the fluororesin particles evenly in the dispersion solution and agglomerations appear in the layer containing these particles, creating defects in the coating and significantly reducing the quality of image from the outset of initial printing.
Another known technology uses small-diameter fluororesin particles as means to effectively reduce the friction coefficient of the surface of the photosensitive member. When small-diameter particles are used, the surface area increases even where an equal number of parts by weight of the particles are added, effectively reducing the friction coefficient. However, such fluororesin particles do not disperse evenly even when they have a small diameter. It is difficult to form a smooth and even coating having no agglomerations, and the quality of the image from the outset of initial printing is significantly reduced.